1 /* $NetBSD: hash-string.h,v 1.1.1.1 2016/01/14 00:11:27 christos Exp $ */
2
3 /* Description of GNU message catalog format: string hashing function.
4 Copyright (C) 1995, 1997-1998, 2000-2003 Free Software Foundation, Inc.
5
6 This program is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Library General Public License as published
8 by the Free Software Foundation; either version 2, or (at your option)
9 any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Library General Public License for more details.
15
16 You should have received a copy of the GNU Library General Public
17 License along with this program; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
19 USA. */
20
21 /* @@ end of prolog @@ */
22
23 /* We assume to have `unsigned long int' value with at least 32 bits. */
24 #define HASHWORDBITS 32
25
26
27 /* Defines the so called `hashpjw' function by P.J. Weinberger
28 [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools,
29 1986, 1987 Bell Telephone Laboratories, Inc.] */
30 static inline unsigned long int
hash_string(const char * str_param)31 hash_string (const char *str_param)
32 {
33 unsigned long int hval, g;
34 const char *str = str_param;
35
36 /* Compute the hash value for the given string. */
37 hval = 0;
38 while (*str != '\0')
39 {
40 hval <<= 4;
41 hval += (unsigned char) *str++;
42 g = hval & ((unsigned long int) 0xf << (HASHWORDBITS - 4));
43 if (g != 0)
44 {
45 hval ^= g >> (HASHWORDBITS - 8);
46 hval ^= g;
47 }
48 }
49 return hval;
50 }
51